Then your grandparents are technical users. Curiously, so are mine. Sorry to tell you that you're wrong though and you have not met the non-technical users.

I've had to try to help my aunt and uncle recover old Apple and Google accounts with complete failure because they've changed cell phone providers and didn't care that their phone numbers changed. At no point are they adequately warned this is the case, and recovery codes are a confusing additional layer that they don't understand.

So they basically lose everything and nobody is willing to help them. You are making a grand assumption about accessibility - not everyone has the capability to grok such a convoluted login process. The non-technical users often aren't morons - they are just differently abled. Maybe they are immigrants who didn't grow up with computers much because they were poor, or have a mental condition.

2FA fails spectacularly on accessibility.

Your reply is an example of the problem - completely oblivious to the users that are horribly underserved by 2FA as it exists.

You do not need to be a programmer or work in IT to know how to use a computer effectively.

On the other hand there are people that do not use computers nor smartphone features that aren't also offered in feature phones.

[0] https://www.etymonline.com/word/technical#etymonline_v_7660